//读取 前面16位short,后32位int,后面就全是string的例子 http://blog.csdn.net/woxingwosu0100/article/details/51273523
//要了解 FileReader
var reader = {
    readAs: function (type, blob, cb) {
        var r = new FileReader();
        r.onloadend = function () {
            if (typeof (cb) === 'function') {
                cb.call(r, r.result);
            }
        }
        try {
            r['readAs' + type](blob);
        } catch (e) { }
    }
}


function parseBlob(blob,cbFn) {   
    var retStr = '__parseBlob__'
    reader.readAs('Text',blob, function (result) { //blob.slice(6, blob.size, 'text/plain;charset=UTF-8')
        //这个函数是异步执行的
        stringVar = result;
        retStr = stringVar;
        //console.log('stringVar', stringVar);
        if (cbFn) {
            cbFn(retStr);
        }
    });
    //console.log('retStr', retStr);   
    return retStr;
}